In the course of a screening program for novel antitumor antibiotics, a new antibiotic, 13-hydroxyglucopiericidin A (1), was isolated from the fermentation broth of Streptomyces sp. OM-5689, along with previously isolated glucopiericidinols A1 (2) and A2 (3). The isolation of 1 involved ethyl acetate extraction of the 70-liter fermentation broth, followed by silica gel chromatography, Sephadex LH-20 chromatography, and preparative TLC purification, yielding 170 mg of the compound. Physicochemical properties (Table 1) indicated it was a glucopiericidin analog: its molecular formula matched those of 2 and 3, but UV spectral data differed from 2 and 3 and resembled glucopiericidins. 1H and 13C NMR spectra (Table 2) were similar to glucopiericidin A (4), with key differences in the C-11–C-13 region: the methyl signal at δ 13.2 (C-13 of 4) was absent in 1, while an oxygenated methylene signal (δ 58.1, t) was present, leading to the structural assignment of 1 as 13-hydroxyglucopiericidin A. Biological characterization showed 1 had no antimicrobial activity at 1000 μg/ml against various bacteria and fungi, but exhibited weak inhibitory activity against Piricularia oryzae KF180 (MIC 500 μg/ml) and cytocidal activity against B16 melanoma cells (as indicated by fraction collection during isolation).